For measuring the load current of a power transistor (particularly of an IGBT or a MOSFET) so-called sense-transistor arrangements are commonly used. An early publication of such a sense-transistor arrangement is, for example, the U.S. Pat. No. 5,023,693. In particular when using the power transistor as a high side semiconductor switch the load current may have to be measured at high DC potentials. Measuring current at a high DC potential usually requires the use of high voltage circuit components in the measurement circuit. Such high voltage components entail a more complex circuit design and require a large amount of chip area. Especially, when the measurement result is provided as a digital value the requirement for a high proof-voltage includes considerable problems in the circuit design. Thus, there is a need for a current measurement circuit which allows for current measurement at high DC potentials with only a few high voltage circuit components.